so i sent in a trident to have it serviced and they sent me back a refurbished. the unit connects on initial set up and primes fine, but once it does the test, it fails b test. i can get the alk reading but stops at b. I can see the water in the test tube as well as the reagent when looking at it. i looked at all the hoses and solenoid but see no issue. i did the neptunes troubleshoot and ran out of ideas. without re-sending it back in, anyone else have any suggestions?